This research program is primarily concerned with the analysis of the function of the lactose operon in E. coli. Our current work can be divided into four main categories: (1) polarity and translational punctuation, which includes work on the isolation of peptide fragments and on the complementation of Beta-galactosidase; (2) the study of the mechanism by which aberrant proteins are rapidly degraded in E. coli; (3) the mechanism by which phage Mu-1 integrates into the coli chromosome; and (4) the study of a phenomenon which we have recently discovered and called polypeptide splicing, in which one protein is formed from the products of two mutant lac operons.